I-5 - 116th St NE Interchange - Tulalip Tribes Lead

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Overview
The Tulalip Tribes are reconstructing the existing Interstate 5 interchange at 116th Street Northeast with a new Single-Point Urban Interchange (SPUI). This will increase capacity, reduce delays and improve turning movements to move more cars through the interchange more efficiently.
The Tulalip Tribes took the lead in planning this four phase transportation improvement project. Partners include WSDOT, the Federal Highway Administration, Bureau of Indian Affairs, Snohomish County, and the City of Marysville.

Why is WSDOT helping replace the interchange at I-5 and 116th Street Northeast?
Off-ramp backups at 116th Street Northeast spill onto the Interstate 5 mainline, which is a Washington state corridor. The delays currently bring traffic crossing the Interstate to a standstill during peak hours. Without a new interchange design to handle the growing population in North Snohomish County, these backups will get worse, further reducing drive times for the 100,000 drivers who use this part of I-5 every day. This interchange services an outlet mall, casino and the second-busiest truck stop on I-5 between Seattle and Canada.

Project Details
This is the fourth and final phase in the diamond interchange replacement project on Interstate 5 at 116th Street Northeast. During this phase, the existing diamond ramps will be realigned into the SPUI configuration. A single traffic signal and new lighting will be added. Crews will also do stormwater and landscaping work, lay down pavement markings, add signage and improve water and sewer infrastructure.

The 3-lane 116th Street Northeast bridge over I-5 was reconstructed with a 6-lane span.

Safety improvements such as temporary signals were installed as well as retaining walls and noise walls.

The End Result
The SPUI will reduce congestion because one signal will control all crossing traffic. This allows more drivers to turn in a single cycle, reducing the backups that occur as traffic waits for turn signals.

Needs & benefits

Economic:

Roughly 11,000 trucks carry 46 million tons of freight through this interchange every day. Congestion at the interchange adds travel time and increases the cost of moving goods along I-5.

Easier access to area businesses such as the outlet mall and casino, will encourage people to revisit this area of Snohomish County.

Safety:

Collision rates may be reduced because one signal will allow all lanes of left-turning traffic through the intersection at the same time without having to yield to on-coming traffic.

The Tulalip Tribes will make some Americans with Disabilities Act (ADA) upgrades to make crossing the bridge over I-5 safer for people who use wheelchairs as well as cyclists, pedestrians and people pushing strollers.

Congestion:

Moving more cars off the interstate, up the ramps and through the intersection will reduce backups onto I-5.

With this project, the Tulalip Tribes estimate the average vehicle delay at this intersection in the peak hours will be reduced from 10 minutes to 54 seconds by the year 2042.

Environmental:

Less idling at the intersection will improve air quality.

Timeline

February 2018: Construction scheduled to start.

Spring 2019: Construction scheduled to be completed.

Funding

The total estimated cost of WSDOT’s contribution to this project is $16.8 million.